Definition: In this task, you are given an input list A comprising of numbers and alphabets. You need to extract and sort the unique alphabets in the list. The alphabets in the input list will only be in lowercase. Return -1 if there is no alphabet in the input list.
Input: ['r', '431', '5369', '2213', 'y', 'r', 'k', '1431', 'n']

k, n, r, y